1. Field of Invention
The field of art to which this invention relates is generally directed to suture anchors and more specifically suture anchors constructed of allograft bone with a bottom clip assembly for receiving and holding the sutures.
2. Description of the Prior Art
As the treatment of injuries to joints and soft tissue has progressed, a need has developed for medical devices which can be used to attach tendons, ligaments and other soft tissue to bone. When surgically repairing an injured joint, it is preferable to restore the joint by reattaching the damaged soft tissues such as ligaments and tendons to bone rather than replacing them with an artificial material.
An increase in the incidence of injuries to joints involving soft tissue has been observed. This increased incidence may be due, at least in part, to an increase in participation by the public in various physical activities such as sports and other recreational activities. These types of activities may increase the loads and stress placed upon joints, sometimes resulting in joint injuries with corresponding damage to associated soft tissue. There are well over 500,000 surgical procedures performed in the United States annually in which soft tissue was attached to a bone in various joints including the shoulder, hip and knee.
One conventional orthopedic procedure for reattaching soft tissue to bone is performed by initially drilling holes or tunnels at predetermined locations through a bone in the vicinity of a joint. The surgeon approximates soft tissue to the surface of the bone using sutures threaded through these holes or tunnels. This method is a time consuming procedure resulting in the generation of numerous bone tunnels. The bone tunnels, which are open to various body fluids and infectious agents, may become infected or break and complications such as longer bone-healing period may result. A known complication of drilling tunnels across bone is that nerves and other soft tissue structures may be injured by the drill bit or orthopaedic pin as it exits the far side of the bone. Also, it may be anatomically impossible or at least very difficult to reach and/or secure a suture that has been passed through a tunnel. When securing the suture or wire on the far side of the bone, nerves and soft tissues can become entrapped and damaged.
Screws are also used to secure soft tissues adjacent to the bone surface. Screws suffer from the disadvantage that they tend to loosen with time, thereby requiring a second operation to remove the loosened screw. In addition, when the screws are set in bone, the heads of the screws frequently protrude above the surface of the bone in which they are set, thereby presenting an abrasive surface which may create wear problems with surrounding tissue. Once a hole has been made in the bone it may be impossible to relocate the hole in a small distance away from its original position due to the disruption of the bone structure created by the initial hole. Finally, the nature of a screw attachment tends to require a flat attachment geometry; the pilot hole must generally be located on a relatively flat section of the bone, and toothed washers must frequently be used in conjunction with the screws to fasten the desired objects to the target bone. As a result of these constraints, it may be necessary to locate the attachment point at less than an optimal position.
Staples are also used to secure soft tissue adjacent the bone surface. Staples suffer from their own set of disadvantages and generally must frequently be removed after they have been in position for some time, thereby necessitating a second operation In addition, staples must generally be positioned so as to maximize their holding power in the bone which may conflict with the otherwise-optimal position for attachment of the objects to bone. Staples have also been known to crack the bone during deployment, or to accidentally transect the object (e.g. soft tissue) being attached to the bone, since it tends to be difficult to precisely control the extent of the staple""s penetration into the bone. Additionally once the staple has been set into the bone the position of the staple is then effectively determined, thereby making it impossible to thereafter adjust the position of the staple or to adjust the degree of tension being applied to the object which is being attached to the bone without setting a new staple.
In order to overcome a number of the problems associated with the use of the conventional soft tissue to bone attachment procedures, suture anchors have been developed and are now frequently used to attach soft tissue to bone. A suture anchor, commonly referred to as a bone anchors, is an orthopedic, medical device which is typically implanted into a cavity drilled into a bone. In the present application, the device will be referred to as a suture anchor. The bone cavity is typically referred to as a bore hole and if it does not extend through the bone is typically referred to as a xe2x80x9cblind holexe2x80x9d. The bore hole is typically drilled through the outer cortical layer of the bone and into the inner cancerous layer. The suture anchor may be engaged in the bore hole by a variety of mechanisms including friction fit, barbs which are forced into the cancellous layer of bone or by threading into pre-threaded bores in the bone mass or using self tapping threads. Suture anchors have many advantages including reduced bone trauma, simplified application procedures, and decreased likelihood of suture failure. Suture anchors may be used in shoulder reconstruction for repairing the glenohumeral ligament and may also be used in surgical procedures involving rotator cuff repair, ankle and wrist repair, bladder neck suspension, and hip replacement.
Suture anchors typically have a hole or opening for receiving a suture. The suture extends out from the bore hole and is used to attach soft tissue. The suture anchors presently described in the art may be made of absorbable materials which absorb over time, or they may be made from various non-absorbable, biocompatible materials. Although most suture anchors described in the art are made from non-absorbable materials, the use of absorbable suture anchors may result in fewer complications since the suture anchor is absorbed and replaced by bone over time. The use of absorbable suture anchors may reduce the likelihood of damage to local joints caused by anchor migration. Moreover, when an absorbable suture anchor is fully absorbed it will no longer be present as a foreign body. It is also advantageous to construct the bone anchor out of allograft cortical bone as this material will result in natural filling in of the bore with bone in the original bone base and the elimination of foreign material from the site.
It is also a problem that most of the bone anchors currently used are prepacked with sutures attached in kit form forcing the surgeon to use a specific type of suture and the hospital to carry large numbers of bone anchors in inventory with varying suture sizes.
A number or prior art patents such as U.S. Pat. Nos. 5,941,882 and 5,733,307 are directed toward threaded bone screws and bone anchors which have grooves or troughs cut longitudinally along the anchor body intersecting the threads to receive sutures during the bone anchor insertion process.
U.S. Pat. No. 5,824,011 is directed toward threaded bone inserts which have channels cut into their bodies to receive driver torque applicators.
U.S. Pat. No. 6,111,164 shows a bone insert which is formed from human cortical bone which are adapted to be driven into bone and U.S. Pat. Nos. 5,858,749 and 5,968,047 disclose bone fixation devices such as bone screws, anchors and the like fabricated from bone tissue.
Although suture anchors for attaching soft tissue to bone are available for use by the orthopedic surgeon, there is a need in this art for novel suture anchors having improved performance characteristics, such as ease of insertion and greater resistance to xe2x80x9cpull-outxe2x80x9d.
The present invention is directed toward a suture anchor constructed of animal bone preferably cortical human bone which is threaded and has a plurality of longitudinal grooves cut into its outer surface intersecting the helical thread to hold suture strands and the drive elements of a driver instrument. The lower distal end is tapered and formed with two separated leg portions, each of which has an inclined inner surface leading to a suture cavity cut in the suture anchor body transverse to the longitudinal axis of the bone anchor body.
The present invention provides a technical advantage in that it provides a channel in the suture anchor in which the suture resides during insertion of the bone anchor into the bone while also allowing the driver to be in the form of a drive socket rather than an end torque applying device to provide a bone anchor that is less susceptible to mechanical breakage.
It is thus an object of the present invention to provide a suture anchor which can be used with a wide variety of sutures from different manufacturers allowing the surgeon the choice of sutures and suture composition, thus saving the hospital from stocking a large number of prepacked bone anchors and suture kits.
Therefore, it is another object of the present invention to provide a suture anchor which is simple to apply and is mechanically stable when implanted in bone.
It is a further object of the present invention to provide an absorbable suture anchor made of cortical bone.
Accordingly, one of the objects of the present invention is to provide an allograft suture anchor which promotes the use of natural bone growth in the bone bore.
Another object of the present invention is to provide a novel suture anchor for anchoring one end of a piece of conventional suture in bone by simply snapping the suture length through an open end into the suture chamber leaving the suture residing free outside the bone so that the free end of the suture can then be used to attach the desired object (e.g. a ligament or prosthesis) to the bone.
Yet another object of the present invention is to provide a novel suture anchor for anchoring one end of a piece of conventional suture in bone which anchor will attach itself securely to the target bone and which has virtually no tendency to migrate from its deployment site.
And another object of the present invention is to provide a novel suture anchor for anchoring one end of a piece of conventional suture in bone which has high tissue acceptability, prevents back out and is reliable in use.
These and other objects, advantages, and novel features of the present invention will become apparent when considered with the teachings contained in the detailed disclosure along with the accompanying drawings.